46131-0598 <90-00018>
P
AGE
35
CIRCUIT BOARD REPLACEMENT
Y
ou can replace the printed circuit boards inside the APU
without having to remove any wiring from the back panel
connectors.
To replace a circuit board:
1.
Turn off power to the APU.
2.
Open the plastic front cover.
3.
Remove the screws in the lower left and lower right corners of the
front panel.
4.
Pull the front panel and circuit boards out from the housing.
5.
Disconnect the 10-position connector in the middle of the main
circuit board.
6.
Disconnect the 20-position connector on the left side of the main
circuit board.
7.
Pull the main circuit board out of the three 56-pin edge connectors
on the front panel.
8.
Remove the screws for the Expansion Board subassembly (-01 and
-21 options) and/or the 202 Modem subassembly (-20 and -21 op-
tions), and carefully pull the board(s) up and out of the plug-in con-
nectors.
9.
Refer to the Switch and Strap Settings section of the Installa-
tion chapter to set the switches and straps on the replacement
board.
10.
Install the Expansion Board subassembly and/or the 202 Modem
subassembly on the main circuit board.
11.
Push the main circuit board into the three 56-pin edge connectors
on the front panel.
12.
Connect the 20-position connector on the left side of the main cir-
cuit board.
13.
Connect the 10-position connector in the middle of the main circuit
board.
14.
Push the front panel and circuit boards into the housing.
15.
Replace the screws in the lower left and lower right corners of the
front panel.
16.
Close the plastic front cover.
17.
Apply power to the APU.
18.
If you replaced the main circuit board, refer to the Configuration
section of the Installation chapter to configure the APU.
19.
If you replaced the 202 modem subassembly, refer to the 202 Mo-
dem Checkout section of the Installation chapter to set the sig-
nal levels.
20.
End of section.
